Probability modelling

Wassup guys.

I have this pain of a math problem that I need help with. There's this question:

"Suppose that the probability of a parent having no offspring is 1/4, and the probability of the parent having two offspring is 3/4. What's the probability that the population will die out in the 4th generation?"

The lecturer insists that there are no errors in the question, grammatical or otherwise.

Re: Probability modelling

Another friend gave me the idea of bacteria, where the birthing process (mitosis) would always yield two offspring, in which case we simply construct a 4-step transition matrix with the states "0" and "1" being "no offpring" and "two offsrping" respectively, then we find P^4(10)...what do you think?